1. Field of the Invention
The present invention relates to a computer system which operates in accordance with a plurality of programs, and more specifically to technology for controlling the giving and receiving of data in memory between such programs.
2. Description of the Related Art
In recent years, accompanying the opening up of computer systems, programs have been used which have the same functions in a variety of systems and a variety of platforms. The giving and receiving of data between programs is generally done by passing parameters. These parameters are passed from top to bottom between programs in a hierarchic structure. Data thus passed includes information which is system specific and information which is platform specific. For that reason, depending upon the system or the platform, data is included that is not absolutely necessary. That is, there are cases in which programs irrelevant to the passed data are involved in the propagation of the data. To prevent this situation, it is desirable to perform efficient giving and receiving of data between programs.
In the past, the method of passing data as parameters and the method of using a common area for use of a control table were known methods of giving and receiving data between programs.
In the method of passing data from top to bottom using parameters, for example in the case in which data is passed from program A to program C in a hierarchic structure of programs A to C, there are systems in which there will exist data not required at program B. In this type of situation, with methods of the past, the data to be passed from program A to program C must needlessly be passed via program B.
In contrast to this, in the method of using a control table, data giving and receiving is performed by using a common area which can be accessed by the related group of programs. When the data attributes and table format changes, it is necessary in this method to change the related programs (that is, to re-code them). Also, in cases in which a given data is expressed as a numerical value in one system but as a character string in another system, it is necessary to either use different control tables for the different systems, or to establish a memory area for the storage of each of he differing format data.
In the above-described method of passing data using parameters, if we consider the case in which, for example, data is to be passed from program A via program B to program C, program B, which is unrelated to the programs involved in the data exchange, must be involved in the propagation of the data, this causing a change in the program B interface, this subsequently requiring changes in programs related to program B. Essentially, arising from the involvement in the propagation of data of a program not required for the propagation of the data, there is the problem of having to change the common interfaces between programs.
In the method which uses a control table for the giving and receiving of data, the problem exist of, if the format of the control table changes, having to change all of the related programs, and in the case in which a given data has different formats in different systems, the problem exists having either to use a different control table between different systems, or to establish an area for the storage of each of data formats. In addition, when the hierarchic depth of the control table becomes great, a problem exists in that it becomes difficult to identify the location at which the desired information is stored, this subsequently increasing the time required to retrieve the information.
In such system as these of the past, in giving and receiving data between programs, there remained the problem of there being no means of providing a common interface between systems and between platforms which passes data without showing the data which is either system specific or platform specific, for use as a common interface between systems or platforms.